The story of Dr Jekyll and Mr Hyde is given a new twist when seen through the innocent eyes of Dr Jekyll's housemaid, Mary Reilly.

Mary (Julia Roberts) is sensitive to the needs and weaknesses of her master, Dr Henry Jekyll (John Malkovich) and is prepared to do almost anything for him. Her trust is a blessing as the doctor embarks on a new, dangerous experiment--one that will bring about a meeting between Mary and Dr Jekyll's sinister assistant Mr Hyde.

Although Mary remains devoted to her brilliant but rather reserved employer, she finds herself attracted to the charms of the mysterious Mr Hyde. Together Mary and Mr Hyde share a terrible secret that will cast both fear and danger on the Jekyll household.

Mary Reilly must confront her own personal demons and dangerous desires if she is to survive and vanquish one of humanity's greatest evils.